Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “POSITRON”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 469 records · Page 26
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Change of Maximum Standardized Uptake Value Slope in Dynamic Triphasic [{sup 18}F]-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography Distinguishes Malignancy From Postradiation Inflammation in Head-and-Neck Squamous Cell Carcinoma: A Prospective Trial

Purpose: To evaluate dynamic [{sup 18}F]-fluorodeoxyglucose (FDG) uptake methodology as a post–radiation therapy (RT) response assessment tool, potentially enabling accurate tumor and therapy-related inflammation differentiation, improving the posttherapy value of FDG–positron emission tomography/computed tomography (FDG-PET/CT). Methods and Materials: We prospectively enrolled head-and-neck squamous cell carcinoma patients who completed RT, with scheduled 3-month post-RT FDG-PET/CT. Patients underwent our standard whole-body PET/CT scan at 90 minutes, with the addition of head-and-neck PET/CT scans at 60 and 120 minutes. Maximum standardized uptake values (SUV{sub max}) of regions of interest were measured at 60, 90, and 120 minutes. The SUV{sub max} slope between 60 and 120 minutes and change of SUV{sub max} slope before and after 90 minutes were calculated. Data were analyzed by primary site and nodal site disease status using the Cox regression model and Wilcoxon rank sum test. Outcomes were based on pathologic and clinical follow-up. Results: A total of 84 patients were enrolled, with 79 primary and 43 nodal evaluable sites. Twenty-eight sites were interpreted as positive or equivocal (18 primary, 8 nodal, 2 distant) on 3-month 90-minute FDG-PET/CT. Median follow-up was 13.3 months. All measured SUV endpoints predicted recurrence. Change of SUV{sub max} slope after 90 minutes more accurately identified nonrecurrence in positive or equivocal sites than our current standard of SUV{sub max} ≥2.5 (P=.02). Conclusions: The positive predictive value of post-RT FDG-PET/CT may significantly improve using novel second derivative analysis of dynamic triphasic FDG-PET/CT SUV{sub max} slope, accurately distinguishing tumor from inflammation on positive and equivocal scans.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2015

Individualized Positron Emission Tomography–Based Isotoxic Accelerated Radiation Therapy Is Cost-Effective Compared With Conventional Radiation Therapy: A Model-Based Evaluation

Purpose: To evaluate long-term health effects, costs, and cost-effectiveness of positron emission tomography (PET)-based isotoxic accelerated radiation therapy treatment (PET-ART) compared with conventional fixed-dose CT-based radiation therapy treatment (CRT) in non-small cell lung cancer (NSCLC). Methods and Materials: Our analysis uses a validated decision model, based on data of 200 NSCLC patients with inoperable stage I-IIIB. Clinical outcomes, resource use, costs, and utilities were obtained from the Maastro Clinic and the literature. Primary model outcomes were the difference in life-years (LYs), quality-adjusted life-years (QALYs), costs, and the incremental cost-effectiveness and cost/utility ratio (ICER and ICUR) of PET-ART versus CRT. Model outcomes were obtained from averaging the predictions for 50,000 simulated patients. A probabilistic sensitivity analysis and scenario analyses were carried out. Results: The average incremental costs per patient of PET-ART were €569 (95% confidence interval [CI] €−5327-€6936) for 0.42 incremental LYs (95% CI 0.19-0.61) and 0.33 QALYs gained (95% CI 0.13-0.49). The base-case scenario resulted in an ICER of €1360 per LY gained and an ICUR of €1744 per QALY gained. The probabilistic analysis gave a 36% probability that PET-ART improves health outcomes at reduced costs and a 64% probability that PET-ART is more effective at slightly higher costs. Conclusion: On the basis of the available data, individualized PET-ART for NSCLC seems to be cost-effective compared with CRT.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2015

Comparison of [{sup 11}C]choline Positron Emission Tomography With T2- and Diffusion-Weighted Magnetic Resonance Imaging for Delineating Malignant Intraprostatic Lesions

Purpose: The purpose of this study was to compare the accuracy of [{sup 11}C]choline positron emission tomography (CHOL-PET) with that of the combination of T2-weighted and diffusion-weighted (T2W/DW) magnetic resonance imaging (MRI) for delineating malignant intraprostatic lesions (IPLs) for guiding focal therapies and to investigate factors predicting the accuracy of CHOL-PET. Methods and Materials: This study included 21 patients who underwent CHOL-PET and T2W/DW MRI prior to radical prostatectomy. Two observers manually delineated IPL contours for each scan, and automatic IPL contours were generated on CHOL-PET based on varying proportions of the maximum standardized uptake value (SUV). IPLs identified on prostatectomy specimens defined reference standard contours. The imaging-based contours were compared with the reference standard contours using Dice similarity coefficient (DSC), and sensitivity and specificity values. Factors that could potentially predict the DSC of the best contouring method were analyzed using linear models. Results: The best automatic contouring method, 60% of the maximum SUV (SUV{sub 60}) , had similar correlations (DSC: 0.59) with the manual PET contours (DSC: 0.52, P=.127) and significantly better correlations than the manual MRI contours (DSC: 0.37, P<.001). The sensitivity and specificity values were 72% and 71% for SUV{sub 60}; 53% and 86% for PET manual contouring; and 28% and 92% for MRI manual contouring. The tumor volume and transition zone pattern could independently predict the accuracy of CHOL-PET. Conclusions: CHOL-PET is superior to the combination of T2W/DW MRI for delineating IPLs. The accuracy of CHOL-PET is insufficient for gland-sparing focal therapies but may be accurate enough for focal boost therapies. The transition zone pattern is a new classification that may predict how well CHOL-PET delineates IPLs.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2015

Single-Institution Experience in the Treatment of Primary Mediastinal B Cell Lymphoma Treated With Immunochemotherapy in the Setting of Response Assessment by {sup 18}Fluorodeoxyglucose Positron Emission Tomography

Purpose: Excellent outcomes obtained after infusional dose-adjusted etoposide, doxorubicin, cyclophosphamide, vincristine, prednisone, and rituximab (R-EPOCH) alone have led some to question the role of consolidative radiation therapy (RT) in the treatment of primary mediastinal B cell lymphoma (PMBL). We reviewed the outcomes in patients treated with 1 of 3 rituximab-containing regimens (cyclophosphamide, doxorubicin, vincristine, prednisone [R-CHOP]; hyperfractionated cyclophosphamide, vincristine, doxorubicin and dexamethasone [R-HCVAD], or R-EPOCH) with or without RT. We also evaluated the ability of positron emission tomography–computed tomography (PET-CT) to identify patients at risk of relapse. Methods and Materials: We retrospectively identified 97 patients with diagnoses of stage I/II PMBCL treated at our institution between 2001 and 2013. The clinical characteristics, treatment outcomes, and toxicity were assessed. We analyzed whether postchemotherapy PET-CT could identify patients at risk for progressive disease according to a 5 point scale (5PS) Deauville score assigned. Results: Among 97 patients (median follow-up time, 57 months), the 5-year overall survival rate was 99%. Of patients treated with R-CHOP, 99% received RT; R-HCVAD, 82%; and R-EPOCH, 36%. Of 68 patients with evaluable end-of-chemotherapy PET-CT scans, 62% had a positive scan (avidity above that of the mediastinal blood pool [Deauville 5PS = 3]), but only 9 patients experienced relapse (n=1) or progressive disease (n=8), all with a 5PS of 4 to 5. Of the 25 patients who received R-EPOCH, 4 experienced progression, all with 5PS of 4 to 5; salvage therapy (RT and autologous stem cell transplantation) was successful in all cases. Conclusion: Combined modality immunochemotherapy and RT is well tolerated and effective for treatment of PMBCL. A postchemotherapy 5PS of 4 to 5, rather than 3 to 5, can identify patients at high risk of progression who should be considered for therapy beyond chemotherapy alone after R-EPOCH.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2015

Impact of Pretreatment Combined {sup 18}F-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography Staging on Radiation Therapy Treatment Decisions in Locally Advanced Breast Cancer

Purpose: To assess the diagnostic performance of pretreatment {sup 18}F-fluorodeoxyglucose positron emission tomography/computed tomography ({sup 18}F-FDG PET/CT) and its impact on radiation therapy treatment decisions in patients with locally advanced breast cancer (LABC). Methods and Materials: Patients with LABC with Eastern Cooperative Oncology Group performance status <2 and no contraindication to neoadjuvant chemotherapy, surgery, and adjuvant radiation therapy were enrolled on a prospective trial. All patients had pretreatment conventional imaging (CI) performed, including bilateral breast mammography and ultrasound, bone scan, and CT chest, abdomen, and pelvis scans performed. Informed consent was obtained before enrolment. Pretreatment whole-body {sup 18}F-FDG PET/CT scans were performed on all patients, and results were compared with CI findings. Results: A total of 154 patients with LABC with no clinical or radiologic evidence of distant metastases on CI were enrolled. Median age was 49 years (range, 26-70 years). Imaging with PET/CT detected distant metastatic disease and/or locoregional disease not visualized on CI in 32 patients (20.8%). Distant metastatic disease was detected in 17 patients (11.0%): 6 had bony metastases, 5 had intrathoracic metastases (pulmonary/mediastinal), 2 had distant nodal metastases, 2 had liver metastases, 1 had pulmonary and bony metastases, and 1 had mediastinal and distant nodal metastases. Of the remaining 139 patients, nodal disease outside conventional radiation therapy fields was detected on PET/CT in 15 patients (10.8%), with involvement of ipsilateral internal mammary nodes in 13 and ipsilateral level 5 cervical nodes in 2. Conclusions: Imaging with PET/CT provides superior diagnostic and staging information in patients with LABC compared with CI, which has significant therapeutic implications with respect to radiation therapy management. Imaging with PET/CT should be considered in all patients undergoing primary staging for LABC.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2015

Ventilation/Perfusion Positron Emission Tomography—Based Assessment of Radiation Injury to Lung

Purpose: To investigate {sup 68}Ga-ventilation/perfusion (V/Q) positron emission tomography (PET)/computed tomography (CT) as a novel imaging modality for assessment of perfusion, ventilation, and lung density changes in the context of radiation therapy (RT). Methods and Materials: In a prospective clinical trial, 20 patients underwent 4-dimensional (4D)-V/Q PET/CT before, midway through, and 3 months after definitive lung RT. Eligible patients were prescribed 60 Gy in 30 fractions with or without concurrent chemotherapy. Functional images were registered to the RT planning 4D-CT, and isodose volumes were averaged into 10-Gy bins. Within each dose bin, relative loss in standardized uptake value (SUV) was recorded for ventilation and perfusion, and loss in air-filled fraction was recorded to assess RT-induced lung fibrosis. A dose-effect relationship was described using both linear and 2-parameter logistic fit models, and goodness of fit was assessed with Akaike Information Criterion (AIC). Results: A total of 179 imaging datasets were available for analysis (1 scan was unrecoverable). An almost perfectly linear negative dose-response relationship was observed for perfusion and air-filled fraction (r{sup 2}=0.99, P<.01), with ventilation strongly negatively linear (r{sup 2}=0.95, P<.01). Logistic models did not provide a better fit as evaluated by AIC. Perfusion, ventilation, and the air-filled fraction decreased 0.75 ± 0.03%, 0.71 ± 0.06%, and 0.49 ± 0.02%/Gy, respectively. Within high-dose regions, higher baseline perfusion SUV was associated with greater rate of loss. At 50 Gy and 60 Gy, the rate of loss was 1.35% (P=.07) and 1.73% (P=.05) per SUV, respectively. Of 8/20 patients with peritumoral reperfusion/reventilation during treatment, 7/8 did not sustain this effect after treatment. Conclusions: Radiation-induced regional lung functional deficits occur in a dose-dependent manner and can be estimated by simple linear models with 4D-V/Q PET/CT imaging. These findings may inform future studies of functional lung avoidance using V/Q PET/CT.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2016

Potential Use of {sup 18}F-fluorodeoxyglucose Positron Emission Tomography–Based Quantitative Imaging Features for Guiding Dose Escalation in Stage III Non-Small Cell Lung Cancer

Purpose: To determine whether previously identified quantitative image features (QIFs) based on {sup 18}F-fluorodeoxyglucose positron emission tomography (FDG-PET) (co-occurrence matrix energy and solidity) are able to isolate subgroups of patients who would receive a benefit or detriment from dose escalation in terms of overall survival (OS) or progression-free survival (PFS). Methods and Materials: Subgroups of a previously analyzed 225 patient cohort were generated with the use of 5-percentile increment cutoff values of disease solidity and primary tumor co-occurrence matrix energy. The subgroups were analyzed with a log-rank test to determine whether there was a difference in OS and PFS between patients treated with 60 to 70 Gy and those receiving 74 Gy. Results: In the entire patient cohort, there was no statistical difference in terms of OS or PFS between patients receiving 74 Gy and those receiving 60 to 70 Gy. It was qualitatively observed that as disease solidity and primary co-occurrence matrix energy increased, patients receiving 74 Gy had an improved OS and PFS compared with those receiving 60 to 70 Gy. The opposite trend (detriment of receiving 74 Gy) was also observed regarding low values of disease solidity and primary co-occurrence matrix energy. Conclusions: FDG-PET–based QIFs were found to be capable of isolating subgroups of patients who received a benefit or detriment from dose escalation.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2016

Fluorodeoxyglucose Uptake on Positron Emission Tomography Is a Useful Predictor of Long-Term Pain Control After Palliative Radiation Therapy in Patients With Painful Bone Metastases: Results of a Single-Institute Prospective Study

Purpose: To determine whether fluorodeoxyglucose positron emission tomography (FDG-PET) before and after palliative radiation therapy (RT) can predict long-term pain control in patients with painful bone metastases. Methods and Materials: Thirty-one patients with bone metastases who received RT were prospectively included. Forty painful metastatic treatment fields were evaluated. All patients had undergone pre-RT and post-RT PET/CT scanning. We evaluated the relationships between the pre-RT, post-RT, and changes in maximum standardized uptake value (SUV{sub max}) and the pain response, and between SUV{sub max} and pain relapse of the bone metastases in the treatment field. In addition, we compared the SUV{sub max} according to the length of time from the completion of RT to pain relapse of the bone metastases. Results: Regarding the pain response at 4 weeks after the completion of RT, there were 36 lesions of 27 patients in the responder group and 4 lesions of 4 patients in the nonresponder group. Changes in the SUV{sub max} differed significantly between the responder and nonresponder groups in both the early and delayed phases (P=.0292 and P=.0139, respectively), but no relationship was observed between the pre-RT and post-RT SUV{sub max} relative to the pain response. The responder group was evaluated for the rate of relapse. Thirty-five lesions of 26 patients in the responder group were evaluated, because 1 patient died of acute renal failure at 2 months after RT. Twelve lesions (34%) showed pain relapse, and 23 lesions (66%) did not. There were significant differences between the relapse and nonrelapse patients in terms of the pre-RT (early/delayed phases: P<.0001/P<.0001), post-RT (P=.0199/P=.0261), and changes in SUV{sub max} (P=.0004/P=.004). Conclusions: FDG-PET may help predict the outcome of pain control in the treatment field after palliative RT for painful bone metastases.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2016

Prognostic Role of Pre–Radiation Therapy {sup 18}F-Fluorodeoxyglucose Positron Emission Tomography for Primary Mediastinal B-Cell Lymphomas Treated with R-CHOP or R-CHOP-Like Chemotherapy Plus Radiation

Purpose: To validate, in a monoinstitutional cohort with extended follow-up, that post–rituximab chemotherapy (R-CT) {sup 18}F-fluorodeoxyglucose positron emission tomography ({sup 18}FDG-PET) is a prognostic factor allowing discrimination of primary mediastinal B-cell lymphoma (PMBCL) patients at higher risk for progression after radiation therapy. Methods and Materials: We analyzed 51 patients, and {sup 18}FDG-PET scans were re-examined evaluating both the Deauville 5-point scale (D5PS) score and the standardized uptake value (SUV) of residual activity, if present. These parameters were then tested by univariate analysis for a potential correlation with progression-free survival (PFS) as the primary study endpoint. Results: Median follow-up time was 51 months (range, 9-153 months). After R-CT, D5PS score was 1 in 10 (19.6%), 2 in 11 (21.6%), 3 in 7 (13.8%), 4 in 17 (33.3%), and 5 in 6 patients (11.7%). Forty-three out of 51 patients (84.3%) had an SUV{sub max} ≤5, and 8 out of 51 (15.7%) had an SUV{sub max} ≥5. Overall, 6 patients experienced progression or relapse: 1 had a D5PS score 2 (with SUV{sub max} ≤5), and 5 had a D5PS score 5 (and SUV{sub max} ≥5). Patients with a D5PS score 5 showed significantly lower PFS rates versus all other scores (log-rank P<.001), as did patients with SUV{sub max} ≥5 when compared with those with SUV{sub max} ≤5 (log-rank P<.001). Conclusions: The present study confirmed the prognostic role of {sup 18}FDG-PET after R-CT, with patients with a D5PS score of 5 and/or an SUV{sub max} ≥5 being at high risk of progression/relapse after RT.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2016

Using [{sup 18}F]Fluorothymidine Imaged With Positron Emission Tomography to Quantify and Reduce Hematologic Toxicity Due to Chemoradiation Therapy for Pelvic Cancer Patients

Purpose: The purpose of the present prospective clinical trial was to determine the efficacy of [{sup 18}F]fluorothymidine (FLT)-identified active bone marrow sparing for pelvic cancer patients by correlating the FLT uptake change during and after chemoradiation therapy with hematologic toxicity. Methods and Materials: Simulation FLT positron emission tomography (PET) images were used to spare pelvic bone marrow using intensity modulated radiation therapy (IMRT BMS) for 32 patients with pelvic cancer. FLT PET scans taken during chemoradiation therapy after 1 and 2 weeks and 30 days and 1 year after completion of chemoradiation therapy were used to evaluate the acute and chronic dose response of pelvic bone marrow. Complete blood counts were recorded at each imaging point to correlate the FLT uptake change with systemic hematologic toxicity. Results: IMRT BMS plans significantly reduced the dose to the pelvic regions identified with FLT uptake compared with control IMRT plans (P<.001, paired t test). Radiation doses of 4 Gy caused an ∼50% decrease in FLT uptake in the pelvic bone marrow after either 1 or 2 weeks of chemoradiation therapy. Additionally, subjects with more FLT-identified bone marrow exposed to ≥4 Gy after 1 week developed grade 2 leukopenia sooner than subjects with less marrow exposed to ≥4 Gy (P<.05, Cox regression analysis). Apparent bone marrow recovery at 30 days after therapy was not maintained 1 year after chemotherapy. The FLT uptake in the pelvic bone marrow regions that received >35 Gy was 18.8% ± 1.8% greater at 30 days after therapy than at 1 year after therapy. The white blood cell, platelet, lymphocyte, and neutrophil counts at 1 year after therapy were all lower than the pretherapy levels (P<.05, paired t test). Conclusions: IMRT BMS plans reduced the dose to FLT-identified pelvic bone marrow for pelvic cancer patients. However, reducing hematologic toxicity is challenging owing to the acute radiation sensitivity (∼4 Gy) and chronic suppression of activity in bone marrow receiving radiation doses >35 Gy, as measured by the FLT uptake change correlated with the complete blood cell counts.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2016

Image Guided Planning for Prostate Carcinomas With Incorporation of Anti-3-[18F]FACBC (Fluciclovine) Positron Emission Tomography: Workflow and Initial Findings From a Randomized Trial

Purpose: {sup 18}F-Fluciclovine (anti-1-amino-3-[{sup 18}F]fluorocyclobutane-1-carboxylic acid) is a novel positron emission tomography (PET)/computed tomography (CT) radiotracer that has demonstrated utility for detection of prostate cancer. Our goal is to report the initial results from a randomized controlled trial of the integration of {sup 18}F-fluciclovine PET-CT into treatment planning for defining prostate bed and lymph node target volumes. Methods and Materials: We report our initial findings from a cohort of 41 patients, of the first enrolled on a randomized controlled trial, who were randomized to the {sup 18}F-fluciclovine arm. All patients underwent {sup 18}F-fluciclovine PET-CT for the detection of metabolic abnormalities and high-resolution CT for treatment planning. The 2 datasets were registered first by use of a rigid registration. If soft tissue displacement was observable, the rigid registration was improved with a deformable registration. Each {sup 18}F-fluciclovine abnormality was segmented as a percentage of the maximum standard uptake value (SUV) within a small region of interest around the lesion. The percentage best describing the SUV falloff was integrated in planning by expanding standard target volumes with the PET abnormality. Results: In 21 of 55 abnormalities, a deformable registration was needed to map the {sup 18}F-fluciclovine activity into the simulation CT. The most selected percentage was 50% of maximum SUV, although values ranging from 15% to 70% were used for specific patients, illustrating the need for a per-patient selection of a threshold SUV value. The inclusion of {sup 18}F-fluciclovine changed the planning volumes for 46 abnormalities (83%) of the total 55, with 28 (51%) located in the lymph nodes, 11 (20%) in the prostate bed, 10 (18%) in the prostate, and 6 (11%) in the seminal vesicles. Only 9 PET abnormalities were fully contained in the standard target volumes based on the CT-based segmentations and did not necessitate expansion. Conclusions: The use of {sup 18}F-fluciclovine in postprostatectomy radiation therapy planning was feasible and led to augmentation of the target volumes in the majority (30 of 41) of the patients studied.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2016

{sup 18}F-Fluorodeoxyglucose Positron Emission Tomography Can Quantify and Predict Esophageal Injury During Radiation Therapy

Purpose: We sought to investigate the ability of mid-treatment {sup 18}F-fluorodeoxyglucose positron emission tomography (PET) studies to objectively and spatially quantify esophageal injury in vivo from radiation therapy for non-small cell lung cancer. Methods and Materials: This retrospective study was approved by the local institutional review board, with written informed consent obtained before enrollment. We normalized {sup 18}F-fluorodeoxyglucose PET uptake to each patient's low-irradiated region (<5 Gy) of the esophagus, as a radiation response measure. Spatially localized metrics of normalized uptake (normalized standard uptake value [nSUV]) were derived for 79 patients undergoing concurrent chemoradiation therapy for non-small cell lung cancer. We used nSUV metrics to classify esophagitis grade at the time of the PET study, as well as maximum severity by treatment completion, according to National Cancer Institute Common Terminology Criteria for Adverse Events, using multivariate least absolute shrinkage and selection operator (LASSO) logistic regression and repeated 3-fold cross validation (training, validation, and test folds). This 3-fold cross-validation LASSO model procedure was used to predict toxicity progression from 43 asymptomatic patients during the PET study. Dose-volume metrics were also tested in both the multivariate classification and the symptom progression prediction analyses. Classification performance was quantified with the area under the curve (AUC) from receiver operating characteristic analysis on the test set from the 3-fold analyses. Results: Statistical analysis showed increasing nSUV is related to esophagitis severity. Axial-averaged maximum nSUV for 1 esophageal slice and esophageal length with at least 40% of axial-averaged nSUV both had AUCs of 0.85 for classifying grade 2 or higher esophagitis at the time of the PET study and AUCs of 0.91 and 0.92, respectively, for maximum grade 2 or higher by treatment completion. Symptom progression was predicted with an AUC of 0.75. Dose metrics performed poorly at classifying esophagitis (AUC of 0.52, grade 2 or higher mid treatment) or predicting symptom progression (AUC of 0.67). Conclusions: Normalized uptake can objectively, locally, and noninvasively quantify esophagitis during radiation therapy and predict eventual symptoms from asymptomatic patients. Normalized uptake may provide patient-specific dose-response information not discernible from dose.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2017

Positron Emission Tomography/Computed Tomography Assessment After Immunochemotherapy and Irradiation Using the Lugano Classification Criteria in the IELSG-26 Study of Primary Mediastinal B-Cell Lymphoma

Purpose: To assess the predictive value of {sup 18}F-fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) for disease recurrence after immunochemotherapy (R-CHT) and mediastinal irradiation (RT), using the recently published criteria of the Lugano classification to predict outcomes for patients with primary mediastinal large B-cell lymphoma. Methods and Materials: Among 125 patients prospectively enrolled in the IELSG-26 study, 88 were eligible for central review of PET/CT scans after completion of RT. Responses were evaluated using the 5-point Deauville scale at the end of induction R-CHT and after consolidation RT. According to the Lugano classification, a complete metabolic response (CMR) was defined by a Deauville score (DS) ≤3. Results: The CMR (DS1, -2, or -3) rate increased from 74% (65 patients) after R-CHT to 89% (78 patients) after consolidation RT. Among the 10 patients (11%) with persistently positive scans, the residual uptake after RT was slightly higher than the liver uptake in 6 patients (DS4; 7%) and markedly higher in 4 patients (DS5; 4%): these patients had a significantly poorer 5-year progression-free survival and overall survival. At a median follow-up of 60 months (range, 35-107 months), no patients with a CMR after RT have relapsed. Among the 10 patients who did not reach a CMR, 3 of the 4 patients (positive predictive value, 75%) with DS5 after RT had subsequent disease progression (within the RT volume in all cases) and died. All patients with DS4 had good outcomes without recurrence. Conclusions: All the patients obtaining a CMR defined as DS ≤3 remained progression-free at 5 years, confirming the excellent negative predictive value of the Lugano classification criteria in primary mediastinal large B-cell lymphoma patients. The few patients with DS4 also had an excellent outcome, suggesting that they do not necessarily require additional therapy, because the residual {sup 18}F-fluorodeoxyglucose uptake may not reflect persistent lymphoma.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2017

{sup 18}F-Choline Positron Emission Tomography/Computed Tomography and Multiparametric Magnetic Resonance Imaging for the Detection of Early Local Recurrence of Prostate Cancer Initially Treated by Radiation Therapy: Comparison With Systematic 3-Dimensional Transperineal Mapping Biopsy

Purpose: To compare the diagnostic performance of {sup 18}F-fluorocholine positron emission tomography/computed tomography (FCH-PET/CT), multiparametric prostate magnetic resonance imaging (mpMRI), and a combination of both techniques for the detection of local recurrence of prostate cancer initially treated by radiation therapy. Methods and Materials: This was a retrospective, single-institution study of 32 patients with suspected prostate cancer recurrence who underwent both FCH-PET/CT and 3T mpMRI within 3 months of one another for the detection of recurrence. All included patients had to be cleared for metastatic recurrence. The reference procedure was systematic 3-dimensional (3D)-transperineal prostate biopsy for the final assessment of local recurrence. Both imaging modalities were analyzed by 2 experienced readers blinded to clinical data. The analysis was made per-patient and per-segment using a 4-segment model. Results: The median prostate-specific antigen value at the time of imaging was 2.92 ng/mL. The mean prostate-specific antigen doubling time was 14 months. Of the 32 patients, 31 had a positive 3D-transperineal mapping biopsy for a local relapse. On a patient-based analysis, the detection rate was 71% (22 of 31) for mpMRI and 74% (23 of 31) for FCH-PET/CT. On a segment-based analysis, the sensitivity and specificity were, respectively, 32% and 87% for mpMRI, 34% and 87% for FCH-PET/CT, and 43% and 83% for the combined analysis of both techniques. Accuracy was 64%, 65%, and 66%, respectively. The interobserver agreement was κ = 0.92 for FCH-PET/CT and κ = 0.74 for mpMRI. Conclusions: Both mpMRI and FCH-PET/CT show limited sensitivity but good specificity for the detection of local cancer recurrence after radiation therapy, when compared with 3D-transperineal mapping biopsy. Prostate biopsy still seems to be mandatory to diagnose local relapse and select patients who could benefit from local salvage therapy.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2017

Prostate-Specific Membrane Antigen Positron Emission Tomography–Computed Tomography for Prostate Cancer: Distribution of Disease and Implications for Radiation Therapy Planning

Purpose: To explore the prostate-specific membrane antigen (PSMA)–avid distribution of prostate cancer (PC) on positron emission tomography (PET), both at the time of initial diagnosis and at the time of relapse after definitive local treatment. Methods and Materials: A total of 179 PSMA PET scans in patients with nil or ≤3 lesions on conventional imaging were retrospectively categorized into 3 subgroups: group A, high-risk PC with no prior definitive therapy (n=34); group B, prior prostatectomy (n=75); and group C, prior radiation therapy (n=70). The numbers and locations of the PSMA-avid lesions were mapped. The PSMA-positive lesions were identified subjectively by a nuclear medicine physician on the basis of clinical experience and taking into account the recent literature and artefacts. Results: A total of 893 PSMA-avid lesions were identified; at least 1 lesion was detected in 80% of all scans. A high detection rate was present even at very low serum PSA levels (eg, at PSA ≤0.20 ng/mL in group B, the detection rate was 46%). Thirty-eight percent of studies revealed extrapelvic disease (41%, 31%, and 46% in groups A, B, and C, respectively). Almost one-third of all studies showed only oligometastases (24%, 36%, and 31% in groups A, B, and C, respectively). A large proportion of these (40%) were a solitary lesion. Conclusions: Prostate-specific membrane antigen PET demonstrated a large number of otherwise unknown metastatic lesions. Therefore we recommend PSMA PET for more accurate assessment of disease burden in initial staging of high-risk PC, as well as for restaging in patients with prostate-specific antigen relapse after primary therapies. Furthermore, a high proportion of oligometastases on PSMA PET provides a prime opportunity to investigate the role of targeted local therapies for oligometastatic PCs.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2018

Prognostic Value of [18F]-Fluoromethylcholine Positron Emission Tomography/Computed Tomography Before Stereotactic Body Radiation Therapy for Oligometastatic Prostate Cancer

To investigate the predictive value of [{sup 18}F]-fluoromethylcholine positron emission tomography/computed tomography (PET/CT)-derived parameters on progression-free survival (PFS) in oligometastatic prostate cancer patients treated with stereotactic body radiation therapy (SBRT).

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2021

Primary Mediastinal B Cell Lymphoma in the Positron-Emission Tomography Era Executive Summary of the American Radium Society Appropriate Use Criteria

Primary mediastinal B cell lymphoma (PMBCL) is a highly curable subtype of non-Hodgkin lymphoma that is diagnosed predominantly in adolescents and young adults. Consequently, long-term treatment-related morbidity is critical to consider when devising treatment strategies that include different chemoimmunotherapy strategies with or without radiation therapy. Furthermore, adaptive approaches using the end-of-chemotherapy (EOC) positron emission tomography (PET)/computed tomography (CT) scanning may help to determine which patients may benefit from additional therapies. We aimed to develop evidence-based guidelines for treating these patients.

62 RADIOLOGY AND NUCLEAR MEDICINE↗